Liquid pump

ABSTRACT

A liquid pump includes a container body, a vacuuming device, and a liquid-discharging device. The container body has an upper portion, a lower portion, a vent hole formed in the upper portion, a cap mounted removably on the upper portion for closing the vent hole, a liquid inlet formed in the upper portion, a guide tube connected to the liquid inlet, a liquid outlet formed in the lower portion, and a plug mounted removably on the lower portion for closing the liquid outlet. The vacuuming device is mounted on the container body and is operable so as to reduce air pressure within the container body. The liquid-discharging device includes a connecting rod connected to the plug and movable between a closing position and an opening position. The liquid-discharging device further includes a biasing unit connected to the connecting rod for biasing the connecting rod to the closing position.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority of Taiwanese application No. 091204414, filed on Apr. 4, 2002.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to a liquid pump, more particularly to a liquid pump suitable for pumping waste motor oil out of an automobile.

[0004] 2. Description of the Related Art

[0005] In a conventional operation for changing waste fluid, such as motor oil, in an automobile, a lifting apparatus is required to lift the automobile before a plug under the automobile can be removed to discharge the waste fluid from the fluid tank into another container body. However, the conventional operation suffers from numerous disadvantages, such as complicated operation and hazardous working conditions.

SUMMARY OF THE INVENTION

[0006] Therefore, the object of the present invention is to provide a liquid pump which is suitable for changing waste fluid, such as motor oil, in an automobile without the need for lifting equipment and without exposing the operator to danger.

[0007] Accordingly, the liquid pump of this invention includes a container body, a vacuuming device, and a liquid-discharging device.

[0008] The container body confines a receiving space, and has an upper portion, a lower portion, a vent hole formed in the upper portion, a cap mounted removably on the upper portion for closing the vent hole, a liquid inlet formed in the upper portion, a guide tube connected to the liquid inlet, a liquid outlet formed in the lower portion, and a plug mounted removably on the lower portion for closing the liquid outlet.

[0009] The vacuuming device is mounted on the container body and is operable so as to reduce air pressure within the container body.

[0010] The liquid-discharging device includes a connecting rod connected to the plug and movable between a closing position, where the plug closes the liquid outlet, and an opening position, where the plug is removed from the liquid outlet. The liquid-discharging device further includes a biasing unit connected to the connecting rod for biasing the connecting rod to the closing position.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiment with reference to the accompanying drawings, of which:

[0012]FIG. 1 is an exploded perspective view of the preferred embodiment of the liquid pump according to this invention;

[0013]FIG. 2 is a sectional view of the liquid pump of FIG. 1;

[0014]FIG. 3 is a sectional view of a check valve of the preferred embodiment;

[0015]FIG. 4 is a fragmentary sectional view showing a state in which a piston is moved from a first end wall to a second end wall of a barrel of the preferred embodiment;

[0016]FIG. 5 is a fragmentary sectional view showing a state in which the piston is moved from the second end wall to the first end wall of the barrel of the preferred embodiment; and

[0017]FIG. 6 is a sectional view of the preferred embodiment in a discharging state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0018] Referring to FIGS. 1 and 2, the preferred embodiment of the liquid pump according to this invention is shown to include a container body 1, a vacuuming device 2, and a liquid-discharging device 3.

[0019] The container body 1 confines a receiving space 10, and has an upper portion 12, a lower portion 11, a vent hole 13 formed in the upper portion 12, a cap 16 mounted removably on the upper portion 12 for closing the vent hole 13, a liquid inlet 14 formed in the upper portion 12, a flexible guide tube 18 connected to the liquid inlet 14, a liquid outlet 15 formed in the lower portion 11, and a plug 17 mounted removably on the lower portion 11 for closing the liquid outlet 15. Preferably, the liquid outlet 15 is formed into a funnel-like shape for quickly and easily discharging the liquid contained in the receiving space 10 of the container body 1 into another container (not shown). The lower portion 11 is formed from a transparent material, such as plastic, into a cylindrical shape, and is secured to the upper portion 12 using any suitable manner, such as by screwing. Furthermore, the lower and upper portions 11, 12 of the container body 1 are assembled in an airtight manner by any suitable way, such as with the use of a seal ring 35. The outer wall of the lower portion 11 is provided with indicia 111.

[0020] The vacuuming device 2 is mounted on the container body 1 and is operable so as to reduce air pressure within the container body 1. The vacuuming device 2 includes a barrel 21, a first end wall 211, a second end wall 212, a check valve 22, a piston 23, and a piston rod 24.

[0021] The barrel 21 is mounted on the container body 1, is formed into a cylindrical shape, confines an air passage 210, and has opposite first and second ends respectively disposed proximate to and distal from the receiving space 10 of the container body 1. The barrel 21 has a wall portion 213 integrally formed with the upper portion 12 of the container body 1.

[0022] The first end wall 211 is mounted on the first end of the barrel 21 using any suitable manner, such as by screwing, and is formed with a plurality of first holes 2111 for fluid communication between the receiving space 10 and the air passage 210. The first end wall 211 is also formed with a center hole 2112. Furthermore, airtight mounting of the first end wall 211 on the first end of the barrel 21 is achieved by any suitable way, such as with the use of a seal ring 34.

[0023] The second end wall 212 is mounted on the second end of the barrel 21 and is formed with a plurality of second holes 2121 for fluid communication between the air passage 210 and the atmosphere externally of the barrel 21.

[0024] The valve 22 is mounted on the first end wall 211 at the center hole 2112 for closing the first holes 2111. As mentioned above, the valve 22 is a check valve which ensures unidirectional air flow from the receiving space 10 to the air passage 210 when there is an air pressure difference therebetween. Referring to FIG. 3, the valve 22 is formed by molding a flexible material into a mushroom-like shape, and includes a holding portion 222, an upper head portion 221 provided on the top of the holding portion 222, and an anchoring portion 223 provided at the bottom of the holding portion 222 and having an outer diameter larger than that of the holding portion 222. The valve 22 is further formed with a hole 224 penetrating through the upper head portion 221, the holding portion 222, and the anchoring portion 223. The length of the holding portion 222 is controlled to make the distance between confronting faces of the head portion 221 and the anchoring portion 223 slightly shorter than the thickness of the first end wall 211 such that the head portion 221 of the valve 22 can block the first holes 2111 in the first end wall 211 by virtue of the flexibility of the head portion 221 of the valve 22.

[0025] Referring again to FIG. 2, the piston 23 is disposed in the barrel 21 and is movable between the first and second end walls 211, 212. The piston rod 24 has a first end portion 241 connected to the piston 23 using any suitable manner, such as by pressing or by screwing, and a second end portion 242 extending through the second end wall 212. The second end portion 242 of the piston rod 24 can be provided with a handle 25 secured thereto using any suitable manner, such as by pressing or by screwing, to facilitate operation of the piston rod 24. The piston 23 divides the air passage 210 into a volume-variable first passage portion 2101 adjacent to the first end wall 211, and a volume-variable second passage portion 2102 adjacent to the second end wall 212.

[0026] The piston 23 includes a first piston plate 231 confronting the first end wall 211, and a second piston plate 232 connected to the first piston plate 231 and confronting the second end wall 212. The outer diameters of the first and second piston plates 231, 232 of the piston 23 are slightly smaller than the inner diameter of the wall portion 213 of the barrel 21 so as to define a first gap 236′ between the first piston plate 231 and the wall portion 213, and a second gap 236 between the second piston plate 232 and the wall portion 213. The first and second piston plates 231, 232 cooperatively form an annular recess 233 therebetween. The annular recess 233 has a depth in an axial direction of the piston rod 24. The second piston plate 232 is formed with a plurality of third holes 234 to communicate the annular recess 233 and the second passage portion 2102. The vacuuming device 2 further includes a seal ring 235 received in and extending along the annular recess 233. The seal ring 235 has a diameter sufficient to establish sealing contact with the barrel 21, and further has a thickness in the axial direction of the piston rod 24 that is less than the depth of the annular recess 233.

[0027] Referring to FIG. 4, when the piston 23 is moved toward the second end wall 212, the seal ring 235 closes the first gap 236′ between the first piston plate 231 of the piston 23 and the wall portion 213 of the barrel 21 so as to block air flow from the first passage portion 2101 into the annular recess 233, and to push air in the second passage portion 2102 out of the air passage 210 via the second holes 2121. At the same time, the valve 22 made of flexible material is opened because of the positive pressure difference between the receiving space 10 and the first passage portion 2101 of the air passage 210 so as to permit air flow from the receiving space 10 into the first passage portion 2101 of the air passage 210.

[0028] Referring to FIG. 5, when the piston 23 is moved toward the first end wall 211, the check valve 22 blocks air flow from the first passage portion 2101 of the air passage 210 to the receiving space 10. At the same time, the seal ring 235 is moved toward the second piston plate 232 of the piston 23 so as to_cause air in the first passage portion 2101 to flow into the second passage portion 2102 via the first gap 236′ between the first piston plate 231 and the wall portion 213 of the barrel 21 and holes 234 formed in the second piston plate 232 of the piston 23.

[0029] Referring again to FIGS. 1 and 2, the liquid-discharging device 3 includes a connecting rod 31 connected to the plug 17 and movable between a closing position, where the plug 17 closes the liquid outlet 15, and an opening position, where the plug 17 is removed from the liquid outlet 15. The liquid-discharging device 3 further includes a biasing unit 32 connected to the connecting rod 31 for biasing the connecting rod 31 to the closing position.

[0030] The connecting rod 31 extends through the hole 224 of the valve 22 mounted on the first end wall 211 and into the first passage portion 2101 of the air passage 210 so as to be capable of being actuated by the piston 23 for movement from the closing position to the opening position. The connecting rod 31 is in intimate contact with the surface that confines the hole 224 of the valve 22 so as to create an airtight effect, which ensures the check valve 22 to function properly. Additionally, the biasing unit 32 includes a perforated stop plate 321 disposed in the air passage 210 and connected to the connecting rod 31, and a spring 322 mounted between the stop plate 321 and the first end wall 211. Furthermore, a guiding unit 33 can be mounted on the connecting rod 31 above the plug 17 for guiding movement of the plug 17 into the liquid outlet 15.

[0031] When the liquid pump of this invention is used for pumping waste motor oil out of the motor oil tank of an automobile, a dip stick is removed so as to create an access to the oil tank for the guide tube 18, an oil filling cap is removed so as to create an air passage between the oil tank and the external atmosphere, the liquid pump is disposed on the ground, and the guide tube 18 is extended into the motor oil tank of the automobile, the latter being in a normal parked states preferably in a horizontal parked state. The cap 16 closes the vent hole 13. The plug 17 is at the closing position. Therefore, the receiving space 10 is in a sealed state.

[0032] Then, the piston 23 of the vacuuming device 2 is moved by repeatedly operating the handle 25 connected to the piston rod 24 between the state shown in FIG. 4 and the state shown in FIG. 5 so as to reduce the air pressure in the receiving space 10 to less than the pressure in the motor oil tank, which is equal to the atmospheric pressure. The air pressure difference between the receiving space 10 and the motor oil tank causes the waste motor oil to flow from the motor oil tank through the guide tube 18 and into the receiving space 10 to achieve pressure equilibrium. When the flow rate of the waste motor oil is reduced, the aforesaid operation for moving the piston 23 can be repeated so as to maintain certain air pressure difference required to cause the waste motor oil remaining within the motor oil tank to flow through the guide tube 18 and into the receiving space 10 until the waste motor oil within the receiving space 10 reaches the indicia 111. The cap 16 is then removed from the vent hole 13 to equalize the pressure in the receiving space 10 and the atmospheric pressure so as to stop the waste motor oil flowing into the receiving space 10.

[0033] Referring again to FIG. 2, in order to prevent the plug 17 from being undesirably removed from the liquid outlet 15 during the operation of pumping waste motor oil into the receiving space 10, the connecting rod 31 is designed to extend through the plug 17 so as to barely touch the ground when the liquid pump is disposed on the ground during the pumping operation.

[0034] Referring to FIG. 6, when waste motor oil is to be discharged from the receiving space 10, the liquid pump is moved above a container (not shown). Then, the connecting rod 31 is actuated by pushing the piston 23 toward the connecting rod 31 so as to move the plug 17 from the closing position to the opening position, thereby discharging the waste motor oil out of the receiving space 10.

[0035] It has thus been shown that the liquid pump of this invention can facilitate pumping of waste motor oil out of an automobile without the need to lift the automobile and without exposing the operator to danger. The object of the invention is thus met.

[0036] While the present invention has been described in connection with what is considered the most practical and preferred embodiment, it is understood that this invention is not limited to the disclosed embodiment but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

I claim:
 1. A liquid pump comprising: a container body confining a receiving space and having an upper portion, a lower portion, a vent hole formed in said upper portion, a cap mounted removably on said upper portion for closing said vent hole, a liquid inlet formed in said upper portion, a guide tube connected to said liquid inlet, a liquid outlet formed in said lower portion, and a plug mounted removably on said lower portion for closing said liquid outlet; a vacuuming device mounted on said container body and operable so as to reduce air pressure within said container body; and a liquid-discharging device including a connecting rod connected to said plug and movable between a closing position, where said plug closes said liquid outlet, and an opening position, where said plug is removed from said liquid outlet, said liquid-discharging device further including a biasing unit connected to said connecting rod for biasing said connecting rod to the closing position.
 2. The liquid pump as claimed in claim 1, wherein said vacuuming device includes: a barrel mounted on said container body, confining an air passage, and having opposite first and second ends respectively disposed proximate to and distal from said receiving space of said container body; a first end wall mounted on said first end of said barrel and formed with a first hole for fluid communication between said receiving space and said air passage; a second end wall mounted on said second end of said barrel and formed with a second hole for fluid communication between said air passage and the atmosphere externally of said barrel; a check valve mounted on said first end wall for closing said first hole; a piston disposed in said barrel and movable between said first and second end walls; and a piston rod having a first end portion connected to said piston, and a second end portion extending through said second end wall; said check valve opening when said piston is moved toward said second end wall so as to permit air flow from said receiving space into said air passage; said check valve closing when said piston is moved toward said first end wall so as to block air flow from said air passage to said receiving space.
 3. The liquid pump as claimed in claim 2, wherein said piston divides said air passage into a volume-variable first passage portion adjacent to said first end wall, and a volume-variable second passage portion adjacent to said second end wall, said piston including a first piston plate confronting said first end wall and a second piston plate connected to said first piston plate and confronting said second end wall, said first and second piston plates cooperatively forming an annular recess therebetween, said annular recess having a depth in an axial direction of said piston rod, said second piston plate being formed with a third hole to communicate said annular recess and said second passage portion, said vacuuming device further including a seal ring received in and extending along said annular recess, said seal ring having a diameter sufficient to establish sealing contact with said barrel, and further having a thickness in the axial direction of said piston rod that is less than the depth of said annular recess.
 4. The liquid pump as claimed in claim 2, wherein said connecting rod extends through said first end wall and into said air passage so as to be capable of being actuated by said piston for movement from the closing position to the opening position.
 5. The liquid pump as claimed in claim 4, wherein said biasing unit includes a stop plate disposed in said air passage and connected to said connecting rod, and a spring mounted between said stop plate and said first end wall. 